Covalent integration of Fe-based metal–organic framework and triazine-containing covalent organic framework for enhanced adsorptive removal of antibiotics

Currently, the issue of antibiotic pollution in water bodies has been increasingly capturing people's attention. The use of high-performance adsorbents for removing antibiotics from water is an effective solution. In this study, NH2-MIL-53(Fe) and triazine-containing Tp-TTA were successfully combined to produce a novel MOF/COF composite named NMF/TT, capable of effectively adsorbing and removing antibiotics. Various characterization techniques were employed to determine the properties and morphology of NMF/TT, and the adsorption performance for four representative antibiotics (tetracycline, ciprofloxacin, ofloxacin, and norfloxacin) was investigated. Results indicated that NMF/TT-90 exhibited the optimal adsorption quantity, significantly enhancing the adsorption quantity compared to the pure components. The adsorption processes of the four antibiotics followed the pseudo-second-order kinetic model and Langmuir isotherm model. Among them, NMF/TT-90 demonstrated the highest adsorption quantity for tetracycline, with a maximum adsorption quantity of 118.48 mg g−1, and also exhibited an adsorption quantity of 55.93 mg g−1 for ciprofloxacin. Thermodynamic results confirmed the spontaneous nature of the adsorption processes for tetracycline and ciprofloxacin. NMF/TT-90 showed the strongest adsorption quantity for tetracycline at pH 7. Furthermore, the effects of adsorbent dosage, interfering ions, real water samples, and the regenerability of the adsorbent were investigated. The high adsorption quantity of the adsorbent is attributed to the π–π interactions, hydrogen bonding, and coordination between NMF/TT-90 and antibiotic molecules, as well as the possible defect effects during the composite formation process.